Heading date and panicle architecture are important agronomic traits in rice. Here, we identified a gene MOTHER OF FT AND TFL1 (OsMFT1) that regulates rice heading and panicle architecture. Overexpressing OsMFT1 delayed heading date by over 7 d and greatly increased spikelets per panicle and the number of branches. In contrast, OsMFT1 knockout mutants had an advanced heading date and reduced spikelets per panicle. Overexpression of OsMFT1 significantly suppressed Ehd1 expression, and Ghd7 up-regulated OsMFT1 expression. Double mutants showed that OsMFT1 acted downstream of Ghd7. In addition, transcription factor OsLFL1 was verified to directly bind to the promoter of OsMFT1 via an RY motif and activate the expression of OsMFT1 in vivo and in vitro. RNA-seq and RNA in situ hybridization analysis confirmed that OsMFT1 repressed expression of FZP and five SEPALLATA-like genes, indicating that the transition from branch meristem to spikelet meristem was delayed and thus more panicle branches were produced. Therefore, OsMFT1 is a suppressor of flowering acting downstream of Ghd7 and upstream of Ehd1, and a positive regulator of panicle architecture.
抽穗期和穗型是水稻的重要農(nóng)藝性狀。本文，我們鑒定了一個(gè)調(diào)控水稻抽穗和穗型的OsMFT1基因。過(guò)表達(dá)OsMFT1使得抽穗期延遲7 d，并顯著增加了每穗穎花數(shù)和分枝數(shù)。相反，OsMFT1敲除突變體的抽穗期提前，而且每穗穎花數(shù)減少。過(guò)表達(dá)OsMFT1顯著抑制Ehd1表達(dá)，而Ghd7上調(diào)OsMFT1表達(dá)。雙突變體顯示OsMFT1在Ghd7下游起作用。此外，OsLFL1轉(zhuǎn)錄因子通過(guò)RY基序與OsMFT1的啟動(dòng)子直接結(jié)合，可在體內(nèi)和體外激活OsMFT1的表達(dá)。RNA-seq和RNA原位雜交分析結(jié)果發(fā)現(xiàn)，OsMFT1抑制FZP和5個(gè)SEPALLATA-like基因的表達(dá)，表明從分枝分生組織向小穗分生組織的轉(zhuǎn)變被延遲，從而產(chǎn)生更多的穗分枝。總結(jié)而言，OsMFT1是一種抑制開(kāi)花的調(diào)控因子，其在Ghd7下游和Ehd1上游起作用，同時(shí)也是水稻穗型的正向調(diào)控因子。